Guidewires are used to assist the insertion of diagnostic and therapeutic catheters into body passages such as arteries and vessels. To guide the catheter to the appropriate location the guidewire is inserted into the patient and advanced through the cardiovascular system while the progress of the guidewire is monitored on an x-ray imaging screen. In some procedures, the guidewire must be advanced and steered through extremely tortuous cardiovascular passageways in order to reach the area to be treated or diagnosed. Accordingly, it is important that the distal tip of the guidewire is flexible to facilitate the advancement and navigation of the guidewire along its tortuous journey. Likewise, a flexible tip is also needed to avoid damaging inner walls of the vessels and arteries with which the tip comes in contact as it is advanced. It has therefore been the subject of much inventive activity to develop guidewires and guidewire tips that are extremely flexible and steerable, so that the guidewire can be easily manipulated into various branches and passages in the vessels and arteries.
Not all catheterization procedures require that the guidewire and catheter be advanced through extremely tortuous pathways. In more routine cases, the physician need only guide the catheter to treat or diagnose regions in primary or otherwise more accessible passage ways of the cardiovascular system. Thus, in more routine cases, it is not necessary to navigate the guidewire through a tortuous pathway. In such cases, the advancements made in extreme flexibility of guidewires and guidewire tips can actually hinder the progress of the physician because, during advancement, the guidewire tends to find and follow side branches and undesired passageways. This increases that amount of work required by the physician and unnecessarily prolongs the duration of an otherwise routine procedure.
There is a need for guidewires for use in routine catheterization procedures that will be less likely to find unwanted side branches and more likely to travel in a generally forward direction. Nevertheless, flexibility is still quite important in any catheterization procedure, both for avoiding trauma to vessel or artery walls and for maintaining steerability. Accordingly, there is a need to provide an easily manufacturable guidewire that has the desired ability to avoid unnecessary detours without sacrificing the flexibility and steerability required of a guidewire.